AGM batteries in the engine bay

[OldGreyFart Advanced Member Find all posts View Profile Close OldGreyFart]

Every bit of advice I read says don't put your second AGM battery in the engine bay. Yet every pic I see on builds on PP has the AGM in the engine bay. And that is where my auto electrician put mine.

Is this like the advice "don't eat bacon - it causes cancer"?

What is going on here?

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

I did in my 120. Wouldn't do it again. Too hot.

[r4ndll Avid PP Poster! Find all posts View Profile Close r4ndll]

Heat is bad for all batteries, not just AGM, it affects the chemical reactions. According to Trojan a month at 35c is equivalent to 2 months at 25C

http://www.trojanbattery.com/pdf/dat...ata_Sheets.pdf

That said. I've got one under my bonnet and its been going strong for 2 years with no issues.

[krypto Avid PP Poster! Find all posts View Profile Close krypto]

I use a thermal cover to stop radiant heat on both batteries. My last one lasted 4 years, no doubt partly killed by excessive discharge when camping

[Lski Member Find all posts View Profile Close Lski]

I put my AGM under the bonnet and have a thermal cover around it. The covers are cheap so even if they reduce the heat on the battery by only a couple of degrees it's worthwhile IMO.

[Hally Senior Member Find all posts View Profile Close Hally]

Where do you get them from the covers

[brogers Advanced Member Find all posts View Profile Close brogers]

Where do you get them from the covers

I got my last one (insulating foil warp for a battery) from Derek at "ABR Sidewinder"

And yes, I had an AGM battery in the engine bay for 4 years...and I did a big trip out back and up north Qld in middle of January a few years with outside temperatures at 50 degrees...the GPS sat nav shut down due to excessive heat..and the battery was still doing its job. I rang the manufacturer and they said you would know if it was damaged as it would start to bulge and swell, and no warranty available if its mounted in the engine bay...unfortunately the metal inner guard under the battery was not so robust..and it cracked eventually...but battery was still going strong.

[Mule Member Find all posts View Profile Close Mule]

Still on my original starter battery well into its 7th year. Deep cycle battery fitted 4 years ago going strong. Both in the engine bay. Heat is but one factor in battery life. The big killer is running them down too much.

[Lski Member Find all posts View Profile Close Lski]

Where do you get them from the covers

Like brogers I got mine from ABR sidewinder also - from memory it was around $15 on ebay

[groeschel Member Find all posts View Profile Close groeschel]

Every bit of advice I read says don't put your second AGM battery in the engine bay. Yet every pic I see on builds on PP has the AGM in the engine bay. And that is where my auto electrician put mine.

Is this like the advice "don't eat bacon - it causes cancer"?

What is going on here?

Interesting subject. Different opinions and different experiences...

I have AGM batteries for both starter and auxiliary under the bonnet ever since I started with AGM batteries which was some 15 years ago
The starter is now probably 5 years old and the auxiliary (which I used as starter before I got the new main battery) is now around 8 years.
According to the voltage meter both holding the voltage well, getting well charged (I use a booster diode) and after some messy experience with spilled acid years ago would not got back.

Saying that that is only my personal experience but keeping them well charged with a voltage above 14V seems to ensure a long life.
Cheers
Mike

[Guest Close Guest]

Saying that that is only my personal experience but keeping them well charged with a voltage above 14V seems to ensure a long life.
Cheers
Mike

Do you do long drives as well?

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

As I have written before, dual battery systems are acompromise, you generally will try
a few different configurations before you come up with the perfect solution for you.

Some AGM's will tolerate heat better than others, the actual car design, where the
battery is placed, does it have a cool air stream to keep it cool etc will have a bearing
on how hot the battery gets, in some cars mounted behind the headlight for example
it will get some cooling air flow, in some cars the aux might be located beside the exhaust
manifold which is not the ideal position to mount a battery etc.

[sweetpea Senior Member Find all posts View Profile Close sweetpea]

Interesting subject. Different opinions and different experiences...

I have AGM batteries for both starter and auxiliary under the bonnet ever since I started with AGM batteries which was some 15 years ago
The starter is now probably 5 years old and the auxiliary (which I used as starter before I got the new main battery) is now around 8 years.
According to the voltage meter both holding the voltage well, getting well charged (I use a booster diode) and after some messy experience with spilled acid years ago would not got back.

Saying that that is only my personal experience but keeping them well charged with a voltage above 14V seems to ensure a long life.
Cheers
Mike

Good to hear.

Have you tested to see what is the capacity if each of the batteries?

Charge it up and stick a moderate load across the battery. I use a 60W or 100W headlight globes which draw about 5 Amps or 8 Amps respectively.

Measure the current.

Leave it run for a few hours and then measure the voltage. Using the nice coloured chart floating around the forum you can work out the SoC and using the current and time you can work out the Amp Hours consumed.

You can then work out the Amp Hours remaining and therefore the actual Amp Hour capacity of the battery.

The volts alone don't tell you the useful energy available from the battery.

S

[peter69_56 Lurker Find all posts View Profile Close peter69_56]

I put a heat shield beside my battery, mounted off the ARB battery mount. Its spaced from the battery with only 2 hold bolts making contact with the battery mounting frame. The shield gets fairly hot but you can feel the difference between the motor side and battery side. With air flow going past the battery and the heat shield the battery remains much cooler.